This invention relates to a bolsterless bogie with air suspension for rail vehicles where an underframe is connected directly by a center pivot and wear-free link to a bogie frame without the intermediary of a bolster beam.
A bogie is known where the underframe is directly linked via the centre pivot through the intermediary of two links each to the bogie. Both links have wear-free joints with one link being arranged horizontally in the direction of travel, whereas the other link is also disposed horizontally but transverse to the direction of travel. The former link will transmit the draw and buffing forces, whereas the latter link is designed to transmit the transverse forces. The region of the plane in which the links are connected to the centre pivot is situated directly below the underframe and appreciably above the level of the axles. Spring action is provided by leaf springs which cushion the swing bolster against the bogie frame.
A bogie arrangement of this type is not only obsolete because of the type of secondary suspension provided and unsuitable for high-speed rail vehicles, but it is also disadvantageous in the way and manner the bogie is linked to the underframe. This drawback is to be seen in the fact that the links are arranged a great distance above the plane of the axles of the wheels. Especially in the case of driving bogies, this tends to displace the wheel loads in a most undesirable manner during acceleration and deceleration, causing skidding or spinning of individual wheel-and-axle sets. Secondly, any pitching motions of the bogie inevitably tend to be transmitted via the center pivot to the car body and to make themselves felt in a detrimental manner in the form of flexural oscillations of the car body and shuttling oscillations. A further disadvantage of this type of connection is to be seen in the unfavourable stressing under extreme operating conditions such as are liable to occur when the cars collide with considerable impact during shunting. Under such conditions, high inertia forces will be transmitted solely by the links and these will be stressed far beyond their normal operating conditions for short periods. This calls for the links to be overdimensioned with a resultant increase in cost.